title: Multi-drug resistant Bacteroides fragilis recovered from blood and severe leg wounds caused by an improvised explosive device (IED) in Afghanistan.
abstract: This report summarizes the case of a 23 year-old otherwise healthy male that was injured in an improvised explosive device (IED) blast in support of Operation Enduring Freedom (OEF). He sustained bilateral open tibia and fibula fractures in the setting of being exposed to water contaminated with raw sewage. Despite long-term carbapenem therapy, the patient's wounds were repeatedly noted to have purulent drainage during surgical debridement and cultures from these wounds were persistently positive for Bacteroides fragilis. Apparent clinical failure persisted despite the addition of metronidazole to his regimen and an eventual trial of tigecycline. Susceptibility testing of the B. fragilis isolate was performed and resistance to penicillin, clindamycin,metronidazole, cefoxitin, meropenem, imipenem, piperacillin/tazobactam, and tigecycline was confirmed. The presence of a nimE gene on a potentially transferrable plasmid was also confirmed by plasmid sequencing. The only antibiotics that displayed in vitro susceptibility were moxifloxacin and linezolid. These antibiotics were initiated in combination with aggressive irrigation and serial surgical debridement. Conversion to left-sided internal fixation became feasible and his left lower extremity was salvaged without residual evidence of infection. The patient completed an eight week course of combination moxifloxacin and linezolid therapy without adverse event. This B. fragilis isolate displayed simultaneous high-level resistance to multiple antibiotics routinely utilized in anaerobic infections. This was evidenced by clinical failure, in vitro susceptibility testing, and demonstration of genes associated with resistance mechanisms. This case warrants review not only due to the rarity of this event but also the potential implications regarding anaerobic infections in traumatic wounds and the success of a novel treatment regimen utilizing combination therapy with moxifloxacin and linezolid.
authors.affiliation: Walter Reed Army Medical Center, Department of Infectious Disease, Washington, DC 20307-5001, USA. jeffrey.e.sherwood@us.army.mil
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Sherwood
authors.forename: Susan
authors.initials: S
authors.lastname: Fraser
authors.forename: Diane M
authors.initials: DM
authors.lastname: Citron
authors.forename: Hana
authors.initials: H
authors.lastname: Wexler
authors.forename: Garry
authors.initials: G
authors.lastname: Blakely
authors.forename: Kelly
authors.initials: K
authors.lastname: Jobling
authors.forename: Sheila
authors.initials: S
authors.lastname: Patrick
mesh_terms: D055826:Afghan Campaign 2001-; D000346:Afghanistan; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D001442:Bacteroides Infections / Q000097:blood / Q000382:microbiology*; D001441:Bacteroides fragilis / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D001753:Blast Injuries / Q000097:blood / Q000382:microbiology*; D024901:Drug Resistance, Multiple, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D007869:Leg Injuries / Q000382:microbiology*; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C094010:NimD protein, Bacteroides fragilis